Gun drill and bore grinding fixture

ABSTRACT

This invention consists of a fixture used in conjunction with modern tool grinding machines making it possible to quickly and accurately grind and regrind the cutting tips of gun drills, gun bores, reamers, etc. This fixture can accomplish the grinding of various point angles, clearance angles, offsets, radii, cylindrical relief, and back slash; also rework of gun drill cutting faces, and clearance slash reliefs, with only one insertion of the tool into the fixture. The invention consists of a rectangular bar to which a front head and a rear head are attached. The front head mounts and clamps in the tool holder of the machine to be used, initially positions the tool to be ground and then supports the front end or tip of the tool during the grinding operation. The rear head is designed to hold and clamp the rear end or shank of the tool to be groung against any forward or backward movement but at the same time allows the tool to be cylindrically rotated and indexed to various positions during the grinding operation.

nited States Patent [19] Mai, Jr.

[ 1 Nov. 5, 1974 GUN DRILL AND BORE GRINDING FIXTURE [76] Inventor:George Mai, Jr., 1270 Fairview Blvd, Windsor, Ontario, Canada [22]Filed: Nov. 12, 1973 [21] Appl. No.: 414,698

Primary Examiner-Harold D. Whitehead Attorney, Agent, or Firm-CharlesKrassov lOll [21314 9|516 [57] ABSTRACT This invention consists of afixture used in conjunction with modern tool grinding machines making itpossible to quickly and accurately grind and regrind the cutting tips ofgun drills, gun bores, reamers, etc. This fixture can accomplish thegrinding of various point angles, clearance angles, offsets, radii,cylindrical relief, and back slash; also rework of gun drill cuttingfaces, and clearance slash reliefs, with only one insertion of the toolinto the fixture. The invention consists of a rectangular bar to which afront head and a rear head are attached. The from head mounts and clampsin the tool holder of the machine to be used, initially positions thetool to be ground and then supports the front end or tip of the toolduring the grinding operation. The rear head is designed to hold andclamp the rear end or shank of the tool to be groung against any forwardor backward movement but at the same time allows the tool to becylindrically rotated and indexed to various positions during thegrinding operation.

1 Claim, 4 Drawing Figures PAIENTED NEW 5 I974 3.845589 SNEEI 1 OF 2 Iaw This invention relates generally to fixtures used in conjunction withtool grinding machines for the purpose of grinding such cutting tools asgun drills, gun bores, reamers, etc.,'and particularly to a fixturewhich allows the grinding of all cutting angles, primary and secondaryrelief angles; and offsets, with only one tool insertion into thefixture.

At the present time there are machines and fixtures available forgrinding these tools. However, in order to accomplish this, manydifferent set-ups are required. The tool whichis being ground has to berelocated within the fixture for each different set-up. This is a muchtime consuming operation, making such grinding costly. Also, withmethods used prior to this invention it was not possible to grind aradius into the tip design of the tool.

Therefore the primary object of this invention is to provide a toolgrinding fixture into which the tool can be inserted and held securelyto perform all the necessary grinding such as pointangles, primary andsecondary clearance angles, offsets with or without radii, and backslashand cylindrical reliefs, without the necessity of removing the cuttingtool from within the fixture.

The many advantages in the use of this invention can be listed asfollows: j

a. One tool insertion and grinding set-up eliminates as many as sevenseparate set-ups, thereby reducing the grinding time to one quarter ofthe time required by present conventional methods.

b. The accuracy and microscopically perfect finish which is a result ofthis method, increases the life span-of the tool, thereby reducing thecost of tools, the cost of grinding, and tool change time.

c. Reduction in the number of scrap production parts. 7

d. Elimination of expensive precision grinding machines and numerousfixtures.

e. Easy operation.

In describing the invention reference will be made to the attacheddrawings in which,

FIG. 1 is a plan view of the invention.

FlG. 2 is anelevation of the invention in section.

FIG. 3 shows the invention located upon a grinding machine.

FIG. 4 shows an enlarged diagram of one style of gun bore cutting end ortip.

The invention consists of a rectangular bar 1 which is used as aconnecting beam, one end has a recessed set screw hole to which a rearhead'body 19 which has a line-up groove 23 is positioned and securelyattached to by means of set screw 17. The other end of said bar has along recessed slot 22 to which a front head 2 is also positioned bymeans of its line-up groove and is secured by set screw 20. The fronthead 2 can be secured anywhere alongthe slot 22 depending upon thelength of the tool to be ground. If longer length adjustment is needed,rectangular bar 1 can be interchanged for a longer one of same design. I

The front head 2 of the fixture is externally shaped to readily fit thetool carriage A of the grinding machine upon which it is to be used. Thehead 2 is provided with a drill bushing 3 to hold the forward head ofthe drill to be ground. Because all drills do not have the same exteriorshape or size, the bushing 3 is interchangeable on its interior to fitthe variousdrills used in a particular establishment. However, itsexterior is kept the same in order to fit its cavity in head 2, whereinit is held by locking screw 21. The head 2 is also provided at its frontend with a centrally located setting finger 4.

The finger 4 rotates upon a dowel 5 and is held in place by a cover 6which is fastened to head 2 by set screw 7. This finger is used toinitially position the cutting edge of the tool to proper center linefor grinding.

The rear head 8 of the fixture is designed to hold and lock securelytherear end or shank 24 of the tool B,

and to cylindrically revolve and index the tool in various positions.The outer body 19 of the rear head 8 is bored to take a press fitted andaxial bushing 13; a sleeve 11 is free to revolve inside said bushing andis held in place in the said rear body by thrust bushing 9 and threadedlocking rings 15 and 16.

An interchangeable tool shank adapter 10 is securely held in sleeve 11by means of a locking screw 18. An indexing cam 12 which can beinterchanged, is fastened to the outside of sleevell by three set screws25, and a spring loaded rocker 14 is mounted on the body 19 and ridesupon and into the grooves of the indexing cam 12.

All the above mentioned parts are hardened and ground to a high degreeof accuracy.

' In order to descibe the operation of the invention, a typical gunbore, the cutting end of which is shown in FIG. 4, is used by way ofexample. This particular gun bore is a standard $41 inch single flute,14 inches long gun bore having cutting angles e 40 and f 20; an offset k0.063 inch; a point radius r 0.005 inch; back slash angle and relief g45; and cutting edge clearances of 15 primary and 25 secondary.

The above described fixture is adjusted for length to fit the length ofthe gun bore by loosening set screw 20, and sliding beam 1 forward orback in alignment slot of front head 2; the screw 20 is then securelytightened. Insert 5 inch bushing 3 into front bore of head 2 and securein place with set screw 21. The fixture is then properly positioned intotool block holder carriage A of the machine to be used. The machine usedin this example is a De Vlieg micropoint grinder equipped with a 320grit diamond wheel. Adjust the grinding machine as per the normaladjusting instructions, i.e., right and left angle protractor stops to20 and 40; roll setting 0; left offset 0.065; radius setting 0.002;upper cylindrical clearance setting 0; lower conical clearance setting15 wheel traverse setting three-fourth; then position wheel head andstart grinder.

Select the proper shank to fixture adapter 10 and fasten it to the shankof the bore by means of the set screw in the adapter. Position cam 12and rocker 14 on rear head'8 into main position and hold groove. Insertgun bore through hole in sleeve 11 and continue through front head 2 andbushing 3, far enough to clear fixture during grinding.

Swivel locating finger 4 to the gun bore point edge and afterpositioning gun bore in proper grinding position, securely lock adapterl0-into rear head 8 with locking screw 18, then swing locating finger 4out of the way.

Using the controls on the Micropoint machine in the prescribed manner,feed and grind the 15 clearance angle on the from 20 and 40 cuttingangles, offset, and radius. Move the lower conical protractor to the 25clearance angle, swing tool carriage A to 40 angle, and secondaryclearance is ground. Rotate bore by means of the rear head revolvingunit between the appropriate stop and location grooves on index cam 12,and the cylindrical relief is ground. Swing carriage A to 20 angle stop,and again rotating rear head unit between the appropriate cam stopgrooves, and the back slash angle and relief are ground.

The grinding operation is now finished and the tool carriage A is backedoff from the grinding wheel. The locking screw 18 is loosened and thebore with the adapter attached thereto is removed from the fixture. Thenthe said adapter is removed from the finished gun bore.

An actual time study of the above regrinding operation by an experiencedgrinding operator, showed it to have taken place in slightly under oneminute. During the grinding operation, an oil mist coolant was used;0.05 inch carbide was removed; and at no time has there been any heatbuild up dangerous to the carbide.

Having described my invention what I claim is:

l. A fixture for use in conjunction with grinding machines for grindinggun drills, gun bores, reamers and other similar tools comprising incombination a rectangular bar, the front end of which is provided with arecessed elongated slot, and the rear end of which is provided with arecessed set screw hole; a front head, the external shape of which fitsinto the holder of the grinding machine, and the underside of which isprovided with a line up groove for slidably adjusting for the length ofthe tool to be held therein and securing the said head to the slot inthe said rectangular bar; an interchangeable drill bushing of variousinternal diameters which is inserted into the forward end of the fronthead and held therein by means of a set screw. for the purpose ofholding the front end of the drill therein; a finger, swivably attachedto the front head, located above the drill bushing and and extendingslightly beyond it, for initially positioning the tool to the propercenter line for grinding; a rear head which is attached to the rear endof said rectangular bar by means of a set screw passing through saidrecessed set screw hole, said rear head being able to contain the shankof the tool to be ground, to hold the tool fixed against forward orbackward movement, and to allow cylindrical and indexed rotation of saidtool; all by means of a bushing located within the body of said rearhead; a sleeve which is fitted inside said bushing, which is free torotate therein, and which is held within said bushing by a thrust washerand locking rings; an interchangeable cam which is indexed with grooveswhich is attached to the outside of said sleeve by a plurality of setscrews; a spring loaded locating rocker mounted on top of the rear headbody which engages the various indexing grooves of said cam; a toolshank adapter to fit individual tool shanks, attached to the end of saidtool shank, and a main locking screw for clamping the tool and itsadapter after insertion into said sleeve of the fixture.

1. A fixture for use in conjunction with grinding machines for grindinggun drills, gun bores, reamers and other similar tools comprising incombination a rectangular bar, the front end of which is provided with arecessed elongated slot, and the rear end of which is provided with arecessed set screw hole; a front head, the external shape of which fitsinto the holder of the grinding machine, and the underside of which isprovided with a line up groove for slidably adjusting for the length ofthe tool to be held therein and securing the said head to the slot inthe said rectangular bar; an interchangeable drill bushing of variousinternal diameters which is inserted into the forward end of the fronthead and held therein by means of a set screw, for the purpose ofholding the front end of the drill therein; a finger, swivably attachedto the front head, located above the drill bushing and and extendingslightly beyond it, for initially positioning the tool to the propercenter line for grinding; a rear head which is attached to the rear endof said rectangular bar by means of a set screw passing through saidrecessed set screw hole, said rear head being able to contain the shankof the tool to be ground, to hold the tool fixed against forward orbackward movement, and to allow cylindrical and indexed rotation of saidtool; all by means of a bushing located within the body of said rearhead; a sleeve which is fitted inside said bushing, which is free torotate therein, and which is held within said bushing by a thrust washerand locking rings; an interchangeable cam which is indexed with grooveswhich is attached to the outside of said sleeve by a plurality of setscrews; a spring loaded locating rocker mounted on top of the rear headbody which engages the various indexing grooves of said cam; a toolshank adapter to fit individual tool shanks, attached to the end of saidtool shank, and a main locking screw for clamping the tool and itsadapter after insertion into said sleeve of the fixture.